Camera body

ABSTRACT

A camera body includes body-side bayonet lugs concentric with lens-side bayonet lugs, circular-arc openings, a circular arc protrusion positioned inside the camera body and projecting forward and concentric with the body-side bayonet lugs, body-side contact portions provided and arranged on the front end surface of the circular arc protrusion and come into contact with lens-side contact portions which are provided on the lens barrel, and rearward biasers provided immediately behind two of the body-side bayonet lugs to bias and move the lens-side bayonet lugs rearward, wherein two of the body-side contact portions located at both ends in the lengthwise direction and the two rearward biasers lie on radial-direction extension lines of the circular arc protrusion, respectively, as viewed in an optical axis direction.

TECHNICAL FIELD

The present invention relates to a camera body.

BACKGROUND ART

Lens-interchangeable cameras which include a camera body and a lensbarrel which can be attached and detached to and from a substantiallycircular opening formed on the front of the camera body are known in theart (e.g., Patent Literatures 1 and 2).

This type of camera body is provided on the edge of the opening thereofwith a plurality of (e.g., three) body-side bayonet lugs which projecttoward the inner peripheral side and is provided behind each body-sidebayonet lug with a biaser which produces a rearward biasing force. Onthe other hand, the interchangeable lens barrel is provided at the rearend thereof with a plurality of (e.g., three) lens-side bayonet lugswhich project toward the outer peripheral side.

When the lens barrel is mounted to the camera body, firstly thelens-side bayonet lugs are inserted into the camera body through aplurality of circular-arc openings each of which is formed betweenadjacent body-side bayonet lugs, and the lens-side bayonet lugs arepositioned immediately behind the body-side bayonet lugs, respectively,by rotating the lens barrel on its optical axis. Thereupon, eachlens-side bayonet lug is biased to move rearward by the associatedbiaser, and the lens-side mount surface that is formed on the lensbarrel comes into contact, from the forward direction, with thebody-side mount surface that is formed on the camera body, so that thelens barrel is fixedly mounted to the camera body.

The lens barrel and the camera body are each provided with a pluralityof contact members, and the contact members of the lens barrel and thecontact members of the camera body are electrically connected only whenthe lens barrel and the camera body are connected at a predeterminedrelative rotational angular position, and therefore, the lens barrel andthe camera body need to be connected at the predetermined relativerotational angular position.

To this end, the body-side bayonet lugs, the circular-arc openings andthe lens-side bayonet lugs are each intentionally made mutuallydifferent in lengthwise dimension (circumferential length) so as toallow each lens-side bayonet lug to be loosely engaged into only thepredetermined circular-arc opening.

Accordingly, even if one attempts to connect the lens barrel and thecamera body to each other at a position other than the predeterminedrelative rotational angular position, the long-size body-side bayonetlug is prevented from entering the camera body by the short-sizecircular-arc opening, and therefore, there is no possibility of the lensbarrel being mistakenly mounted to the camera body at any incorrectrelative rotational angular position.

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Unexamined Patent Publication No.    2010-44203-   Patent Literature 2: Japanese Unexamined Patent Publication No.    2010-117571

SUMMARY OF THE INVENTION Technical Problem

If the lens barrel, in particular, is miniaturized in order tominiaturize the camera, each body-side bayonet lug, each circular-arcopening and each lens-side bayonet lug also become small in lengthwisedimension with the miniaturization of the lens barrel. Accordingly, whenthe camera is miniaturized, large differences in dimensions between thebody-side bayonet lugs, between the circular-arc openings and betweenthe lens-side bayonet lugs cannot be provided, so that each differencein dimensions becomes minute.

However, if each difference in dimension is minute, when one attempts toconnect the lens barrel to the camera body with the axis of the lensbarrel being inclined at a position other than the predeterminedrelative rotational angular position, there is a possibility of thelens-side bayonet lugs passing through the circular-arc openings tothereby cause the lens barrel and the camera body to be improperlymounted to each other.

In addition, when the lens barrel and the camera body are connected,each of the contact members on the lens barrel side and each of thecontact members on the camera body side are required to be reliablyconnected so as to allow a current to properly pass therethrough.Additionally, if the contact members are arranged to have a circular arcshape as viewed from the front side in the case where the lens barrel isminiaturized, the radius of curvature of this circular arc shape becomessmall while the angle occupied by this circular arch shape in thecircumferential direction increases (the angle occupied by this circulararch shape with respect to the circumference of a circle increases), sothat the connected state of each contact portion sometimes becomesunstable.

The present invention provides a camera body which makes it possible toreliably prevent the lens barrel from being mounted to the camera bodyin an improper manner, in which the lens barrel is inclined, and to alsomake each contact member of the lens barrel and the correspondingcontact member of the camera body securely come into contact with eachother with equal pressure, even in the case where the camera and/or thelens barrel are miniaturized.

Solution to Problem

The camera body according to the present invention is characterized byhaving a substantially circular opening formed in a front side thereof,a lens barrel being capable of being attached and detached to and fromthe opening and includes a plurality of circular-arc-shaped lens-sidebayonet lugs which are provided at a rear end of the lens barrel andproject toward an outer peripheral side, and wherein the camera bodyincludes a plurality of body-side bayonet lugs which project from aperipheral edge of the opening toward an inner peripheral side and areconcentric with the lens-side bayonet lugs, wherein the lens-sidebayonet lugs are positioned immediately behind the body-side bayonetlugs when the lens barrel is mounted to the camera body; a plurality ofcircular-arc openings which are formed between the body-side bayonetlugs that are adjacent to one another, wherein the lens-side bayonetlugs pass through the circular-arc openings when the lens barrel ismounted to the camera body; a circular arc protrusion which is providedinside the camera body and projects forward, wherein a central portionof the circular arc protrusion in a lengthwise direction thereof isspaced toward the inner peripheral side from one of the circular arcopenings, wherein both sides of the circular arc protrusion in thelengthwise direction are positioned at an inner peripheral side of twoof the body-side bayonet lugs, respectively, and wherein the circulararc protrusion is concentric with the body-side bayonet lugs; aplurality of body-side contact portions which are provided on a frontend surface of the circular arc protrusion and are arranged thereon inthe lengthwise direction of the circular arc protrusion, wherein thebody-side contact portions come into contact with lens-side contactportions which are provided on the lens barrel when the body-sidebayonet lugs are positioned immediately behind the lens-side bayonetlugs; and two rearward biasers which are provided immediately behind twoof the body-side bayonet lugs, respectively, to bias and move thelens-side bayonet lugs rearward. Two of the body-side contact portionswhich are located at both ends in the lengthwise direction and the tworearward biasers lie on radial-direction extension lines of the circulararc protrusion, respectively, as viewed in an optical axis direction.

The body-side contact portions can be held in the circular arcprotrusion to be capable of advancing and retracting, and the camerabody can include a contact biaser which is provided in the circular arcprotrusion to bias and move the body-side contact portions forward.

The circular arc protrusion can protrude to a position substantiallyidentical to a position of the body-side bayonet lugs in a directionorthogonal to the body-side mount surface.

A circular arc space can be formed between the peripheral edge of theopening of the camera body and the circular arc protrusion, and acircular arc portion of the lens barrel can be positioned in thecircular arc space when the camera body is rotated relative to thecamera body with the body-side bayonet lugs positioned behind thelens-side bayonet lugs.

Advantageous Effects of the Invention

According to the present invention, the lens barrel can be mounted tothe camera body since each lens-side bayonet lug can pass through thecorresponding circular arc opening when the lens barrel, in a disengagedstate from the camera body, is brought close to the camera body with theaxis (optical axis) of the lens barrel being aligned with the centeraxis of the opening of the camera body.

On the other hand, bringing the lens barrel close to the camera bodywhile the axis of the lens barrel is inclined to the aforementionedcenter axis causes any one of lens-side bayonet lugs to come intocontact with the circular arc protrusion, which makes it impossible foreach lens-side bayonet lug to pass through the corresponding circulararc opening. Accordingly, the lens barrel can be reliably prevented frombeing mounted to the camera body in an improper manner, in which theaxis of the lens barrel is inclined to the aforementioned center axis.

In addition, the plurality of lens-side contact portions and theplurality of body-side contact portions can be securely brought intocontact with each other with equal pressure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is front perspective view of an embodiment of a camera accordingto the present invention.

FIG. 2 is a front perspective view of the camera body.

FIG. 3 is a front elevational view of the camera body.

FIG. 4 is a rear perspective view of the lens barrel, wherein the barrelbody thereof is abbreviated.

FIG. 5 is a rear elevational view of the lens barrel, wherein the barrelbody thereof is abbreviated.

FIG. 6 is a side elevational view of the lens barrel, illustrating onlyan upper half thereof as a cross section taken along the line VI-VIshown in FIG. 5, wherein the barrel body is shown by an imaginary line.and

FIG. 7 is a longitudinal sectional view of a central portion of thecamera taken along the line VII-VII shown in FIG. 1, wherein the barrelbody and the external casing are schematically simplified and shown byimaginary lines.

DESCRIPTION OF EMBODIMENT

An embodiment according to the present invention will be hereinafterdiscussed with reference to the attached drawings. Forward and rearwarddirections, leftward and rightward directions, and upward and downwarddirections that are described in the following description are definedbased on the directions of arrows shown in the drawings.

As shown in the drawings, the present embodiment of the camera 10 isprovided with a camera body 20 and a lens barrel 50 which can beattached and detached to and from each other.

The camera body 20 is provided with a hollow external casing 21. Aplurality of operating buttons are provided on the upper and frontsurfaces of the external casing 21, and an LCD is provided on the backof the external casing 21. A circular opening hole 22 is formed in acentral portion of the front of the external casing 21, and a body-sidemount ring 23 made of metal which has a substantially ring shape isfitted into the opening hole 22 and fixed thereto. The inner peripheralside portion of the front of the body-side mount ring 23 is formed as abody-side mount surface 24 which projects a step forward from theposition of the outer peripheral side portion of the front of thebody-side mount ring 23. The body-side mount ring 23 is provided, on theedge of the opening thereof at positions a step rearward from theposition of the body-side mount surface 24, with body-side bayonet lugs25, 26 and 27 which are integrally formed to project toward the innerperipheral side. The body-side bayonet lugs 25, 26 and 27 are circulararc in shape about the center axis of the opening hole 22 (the opticalaxis of the lens barrel 50 when the lens barrel 50 is connected; an axisorthogonal to the body-side mount surface 24) and are provided atsubstantially equi-angular intervals in a circumferential directionabout this center axis. The body-side bayonet lug 26 is greater inlength (circumferential length) than the body-side bayonet lug 27, andthe body-side bayonet lug 25 is even greater in length than thebody-side bayonet lug 26. Additionally, body-side circular-arc openings28, 29 and 30, each of which is circular arc in shape about theaforementioned center axis, are formed between the adjacent body-sidebayonet lugs 25, 26 and 27. As shown in the drawings, the body-sidecircular-arc opening 29, which is formed between the body-side bayonetlugs 25 and 27, is greater in length (circumferential length) than thebody-side circular-arc opening 30, which is formed between the body-sidebayonet lugs 25 and 26, and the body-side circular-arc opening 28, whichis formed between the body-side bayonet lugs 26 and 27, is even greaterin length than the body-side circular-arc opening 29. As shown in FIGS.3 and 7, biasing springs S1, S2 and S3 (rearward biasers) which eachproduce a rearward biasing force by being resiliently deformed forwardlyare arranged at equi-angular intervals of 120 degrees in thecircumferential direction of the mount surface and installed onto therear surfaces of the body-side bayonet lugs 25, 26 and 27, respectively.Additionally, a protrusion 32 which is positioned at a middle positionbetween the body-side bayonet lugs 26 and 27 (i.e., at acircumferentially middle position of the body-side circular-arc opening28) and shorter in length (circumferential length) than the body-sidebayonet lug 27 is integrally projected from the edge of the opening ofthe body-side mount ring 23 at the same position as the body-sidebayonet lugs 25, 26 and 27 with respect to the forward/rearwarddirection. No biasing spring corresponding to the biasing spring S1, S2or S3 is installed onto the rear surface of the protrusion 32. Thedistance (circumferential length) between the protrusion 32 and thebody-side bayonet lug 26 and the distance (circumferential length)between the protrusion 32 and the body-side bayonet lug 27 are eachsmaller than the circumferential length of a lens-side bayonet lug 57which will be discussed later.

A lock pin 34 which extends in the forward/rearward direction isinstalled in a circular hole which is formed in the body-side mountsurface 24 in the vicinity of the lower end thereof. The lock pin 34 isfreely slidable in the forward/rearward direction between a lockedposition, to project forward from the body-side mount surface 24, and anunlocked position, to be fully accommodated in the circular hole, andthe lock pin 34 is biased to move toward the locked position by theforward biasing force of a biaser installed in the circular hole. Inaddition, a lock release button 35 is installed in a hole formed on thefront of the external casing 21. The lock release button 35 is freelyslidable between a non-operating position, to project forward from thefront of the external casing 21, and an operating position, to be fullyaccommodated in the hole, and the lock release button 35 is biased tomove toward the non-operating position by the forward biasing force of abiaser installed in the hole. When the lock release button 35 is in thenon-operating position (when the lock release button 35 is not pressedrearward), the lock pin 34 is in the locked position. When the lockrelease button 35 is in the operating position (when the lock releasebutton 35 is pressed rearward), the lock pin 34 moves to the unlockedposition against the biasing force of the aforementioned biaser.

In the internal space of the external casing 21, an intermediate supportplate 37 made of synthetic resin which has a substantially disk shapeorthogonal to the aforementioned center axis is installed. The entiresurface of the intermediate support plate 37 (which includes a circulararc protrusion 39 which will be discussed later) is black in color, anda surface-texturing process has been performed on this entire surface.As shown in FIG. 7, the outer edge of the intermediate support plate 37is fixed to the outer edge of the rear of the body-side mount ring 23,and a central rectangular aperture 38, in the shape of a rectangle, isformed in a central part of the intermediate support plate 37.

The circular arc protrusion 39, which is positioned immediately abovethe central rectangular aperture 38 and is centered about theaforementioned center axis, is integrally projected forward from thefront of the intermediate support plate 37. Since the opening hole 22(the body-side mount ring 23) is small in diameter, right and leftportions of the circular arc protrusion 39 face the body-side bayonetlugs 25 and 26 in radial directions of the opening hole 22 as viewedfrom front, respectively. In addition, a central portion of the circulararc protrusion 39 radially faces the body-side circular-arc opening 30.A plurality of pin support holes are formed in the front surface of thecircular arc protrusion 39 to be arranged at equal intervals, and metalcontact pins 40, 40 a, 41 and 41 a (body-side contact portions) areinstalled in the pin support holes. The front surface of the circulararc protrusion 39 projects forward to a position substantially identicalto the position of the body-side bayonet lug 26. The contact pins 40, 40a, 41 and 41 a are freely slidable between a projected position (seeFIGS. 2 and 3) to project greatly forward from the front of the circulararc protrusion 39 and a pressed position to be pressed rearward to befully embedded in the circular arc protrusion 39, and the contact pins40, 40 a, 41 and 41 a are biased to move toward the projected positionby forward biasing forces of compression coil springs 42 (see FIG. 7;contact biasers) which are installed in the pin support holes,respectively. As shown in FIG. 7, in a state where the lens barrel 50 ismounted to the camera body 20 (also in a state where the lens barrel 50is not mounted to the camera body 20), the front ends of the contactpins 40, 40 a, 41 and 41 a are positioned behind the body-side mountsurface 24 and in front of the rear surfaces (opposed surfaces) of thebody-side bayonet lugs 25, 26 and 27. The two contact pins 40 and 40 aat the far right are connected to a battery (not shown) which isinstalled in a rear space located behind the intermediate support plate37, and each contact pin 41 and 41 a is connected to a controller (notshown; which is equipped with a CPU, etc.) which is installed in theaforementioned rear space. As viewed from the front, the contact pin 40a at the far right and the biasing spring S1 lie on an extension line(see a one-dot chain line in FIG. 3) of a radial direction of thecircular arc protrusion 39, and the contact pin 41 a at the far left andthe biasing spring S2 lie on an extension line (see a one-dot chain linein FIG. 3) of a radial direction of the circular arc protrusion 39 asshown in FIG. 3.

An image pickup device 44 which is positioned immediately behind thecentral rectangular aperture 38 and immediately below the circular arcprotrusion 39 (in the vicinity of the inner periphery thereof), asviewed from the front, is installed in the aforementioned rear space ofthe external casing 21.

The lens barrel 50 is provided with a barrel body 51 having asubstantially cylindrical shape, and is provided in the barrel body 51with lens groups, a lens drive mechanism which moves the lens groupsforward and rearward in an optical axis direction, a motor which appliesa driving force to the lens drive mechanism, and a memory, etc., inwhich information on specifications (focal length information and thelike) of the lens barrel 50, all of which are not shown in the drawings.

A lens-side mount ring 52, made of metal, which is formed as a circularring-shaped member is fixed to the rear end surface of the barrel body51. The lens-side mount ring 52 is integrally provided with a fixed ringportion 53 which is fixed to the rear end surface of the barrel body 51and a rear surface of which forms a lens-side mount surface 53 a, acylindrical portion 54 which extends rearward from the fixed ringportion 53, and lens-side bayonet lugs 55, 56 and 57 which project fromthe rear end of the cylindrical portion 54 toward the outer peripheralside. The lens-side bayonet lugs 55, 56 and 57 are circular arc in shapeabout the optical axis of the aforementioned lens groups and formed toproject from the cylindrical portion 54 so as to be arranged atsubstantially equi-angular intervals about the optical axis. As shown inthe drawings, the lens-side bayonet lug 56 is greater in length(circumferential length) than the lens-side bayonet lug 57, and thelens-side bayonet lug 55 is even greater in length than the lens-sidebayonet lug 56. In addition, a recessed portion 58 having a circular arcshape is formed in the outer edge of the lens-side bayonet lug 55.Lens-side circular-arc openings 59, 60 and 61, each of which is circulararc in shape about the optical axis, are formed between the adjacentlens-side bayonet lugs 55, 56 and 57. As shown in the drawings, thelens-side circular-arc opening 60, which is formed between the lens-sidebayonet lugs 55 and 57, is greater in length (circumferential length)than the lens-side circular-arc opening 59, which is formed between thelens-side bayonet lugs 55 and 56, and the lens-side circular-arc opening61, which is formed between the lens-side bayonet lugs 56 and 57, isgreater in length than the lens-side circular-arc opening 60.

In addition, the lens-side bayonet lugs 55, 56 and 57 are provided onthe rear edges of the outer peripheral surfaces thereof with roundedsurfaces 55 a, 56 a and 57 a, respectively, each of which is chamferedinto a curved surface having a predetermined radius of curvature.

Additionally, the lens-side bayonet lugs 55, 56 and 57 and the recessedportion 58 correspond in circumferential length and shape to thebody-side circular-arc openings 28, 29 and 30 and the protrusion 32 onthe camera body 20 side, respectively; likewise, the body-side bayonetlugs 25, 26 and 27 and the protrusion 32 on the camera body 20 sidecorrespond in size and shape to the lens-side circular-arc openings 61,60 and 59 and the recessed portion 58 on the lens side, respectively.Accordingly, when the lens barrel 50 is mounted to the camera body 20,the lens-side bayonet lugs 55, 56 and 57 and the recessed portion 58 canenter to a point behind the rear surfaces of the body-side bayonet lugs25, 26 and 27 on the camera body 20 side through the body-sidecircular-arc openings 28, 29 and 30 and the protrusion 32 on the camerabody 20 side, respectively.

In addition, a lock hole 62 is formed in the lens-side mount surface 53a.

An insulating member 63 that is a ring-shaped member made of syntheticresin is fixed to the inner peripheral part of the rear surface of thefixed ring member 53.

Additionally, an inner cylindrical member 66 made of synthetic resin isfixed to the inner peripheral part of the rear surface of the insulatingmember 63. A circular hole 67 through which the aforementioned lensgroups are rearwardly exposed is formed in a center of the rear endsurface of the inner cylindrical member 66.

As shown in FIGS. 4, 5 and 7, a recessed groove 68 in the shape of acircular arc as viewed from rear is formed between the cylindricalportion 54 of the lens-side mount ring 52 and the inner cylindricalmember 66, and a plurality (the same number as the contact points 40, 40a, 41 and 41 a) of contacts 69 (lens-side contact portions), made ofmetal, are fixed to the rear of the insulating member 63, which formsthe bottom of the recessed groove 68, to be arranged at equi-angularintervals in a circumferential direction. The contacts 69 are connectedto the aforementioned motor and memory, etc.

Next, a manner of mounting the lens barrel 50 to the camera body 20 willbe discussed hereinafter.

First, the center axis of the opening hole 22 and the lens optical axisof the lens barrel 50 are brought into alignment with each other, andthe circumferential position of the recessed portion 58 is madecoincident with the protrusion 32; in this state, the rear end of thelens barrel 50 is brought close to the body-side mount ring 23 of thecamera body 20 from front, and subsequently, the lens-side bayonet lug55 is brought into the internal space of the external casing through thebody-side circular-arc opening 28. Subsequently, the lens-side bayonetlug 56 is brought into the internal space of the external casing 21through the body-side circular-arc opening 29, and the lens-side bayonetlug 57 is brought into the internal space of the external casing 21through the body-side circular-arc opening 30. Upon the lens-sidebayonet lug 55 being inserted into the body-side circular-arc opening28, the recessed portion 58 is loosely fitted on the protrusion 32 (therecessed portion 58 passes through the outside of the protrusion 32),and accordingly, the lens-side bayonet lug 55 enters the internal spaceof the external casing 21 without contacting the body-side circular-arcopening 28. Upon the lens-side bayonet lugs 55, 56 and 57 being broughtinto the internal space of the external casing 21 (brought to the rearof the body-side bayonet lugs 25, 26 and 27), the lens-side mountsurface 53 a of the lens barrel 50 comes into contact with the body-sidemount surface 24 of the camera body 20 from the front, and the lock pin34 positioned in the locked position is pressed to the unlocked positionby a portion of the lens-side mount surface 53 a (and simultaneously,the lock release button 35 positioned in the non-operating positionmoves to the operating position). In this state, rotating the entirelens barrel 50 clockwise by an angle of approximately 60 degrees asviewed from the front, causes the lock hole 62 to be positionedimmediately in front of the lock pin 34, which causes the lock pin 34held in the unlocked position by the lens-side mount surface 53 a tomove back to the locked position by the biasing force of theaforementioned biaser (simultaneously causes the lock release button 35in the operating position to move back to the non-operating position bythe biasing force of the aforementioned biaser) to thereupon be engagedin the lock hole 62, which prevents the lens barrel 50 from furtherrotating. Additionally, as shown in FIG. 7, since a portion (circulararc portion) of the cylindrical portion 54 is positioned in arecess-shaped circular-arc space 45 between the circular arc protrusion39 and the body-side mount surface 24, when the lens barrel 50 rotates,the rotating operation of the lens barrel 50 is smoothly performed.Additionally, since the lens-side bayonet lugs 55, 56 and 57 arepositioned immediately behind the body-side bayonet lugs 26, 27 and 25while resiliently deforming the biasing springs S2, S3 and S1 forwardand since the lens-side bayonet lugs 55, 56 and 57 are pressed rearwardby the rearward biasing forces of the biasing springs S2, S3 and S1, thecontact state between the lens-side mount surface 53 a and the body-sidemount surface 24 is maintained. Accordingly, after the lens barrel 50 ismounted to the camera body 20 in this manner, the lens barrel 50 doesnot come off the camera body 20 unless the lock release button 35 isoperated. At this time, the protrusion 32 is located at a differentcircumferential position from the lens-side bayonet lugs 55, 56 and 57.

On the other hand, when the lens barrel 50 is mounted to the camera body20, the lens barrel 50 cannot be mounted to the camera body 20 if thecircumferential position of the recessed portion 58 is not madecoincident with the protrusion 32. For instance, in the case where thelens-side bayonet lug 57, the lens-side bayonet lug 56 and the lens-sidebayonet lug 55 are positioned at the same circumferential positions asthe body-side circular-arc opening 28, the body-side circular-arcopening 30 and the body-side circular-arc opening 29, respectively, thelens-side bayonet lugs 55, 56 and 57 cannot be inserted into theinternal space of the external casing 21 even if the axis of the lensbarrel 50 is made to be inclined with respect to the aforementionedcenter axis of the camera body 20 because the length (circumferentiallength) of the lens-side bayonet lug 57 is far greater than the distancebetween the protrusion 32 and the body-side bayonet lug 26 and thedistance between the protrusion 32 and the body-side bayonet lug 27, thelens-side bayonet lug 56 is greater in length than the body-sidecircular-arc opening 30 and the lens-side bayonet lug 55 is greater inlength than the body-side circular-arc opening 29. Likewise, also in thecase where the lens-side bayonet lug 55, the lens-side bayonet lug 56and the lens-side bayonet lug 57 are positioned at the samecircumferential positions as the body-side circular-arc opening 30, thebody-side circular-arc opening 28 and the body-side circular-arc opening29, respectively, the lens-side bayonet lugs 55, 56 and 57 cannot beinserted into the internal space of the external casing 21 even if theaxis of the lens barrel 50 is made to be inclined with respect to theaforementioned center axis of the camera body 20 because the lens-sidebayonet lug 55 is greater in length (circumferential length) than thebody-side circular-arc opening 30, the lens-side bayonet lug 57 isgreater in length than the body-side circular-arc opening 29, and thelength of the lens-side bayonet lug 56 is far greater than the distancebetween the protrusion 32 and the body-side bayonet lug 26 and thedistance between the protrusion 32 and the body-side bayonet lug 27.

Additionally, if the optical axis of the lens barrel 50 is inclined withrespect to the center axis of the opening hole 22 when the lens barrel50 is mounted to the camera body 20, the lens-side bayonet lug 55, 56 or57 attempts to enter the body-side circular-arc opening 30 in a slantingdirection. However, since this lens-side bayonet lugs 55, 56 or 57 is tocome into contact with a central portion of the circular arc protrusion39, the lens-side bayonet lugs 55, 56 and 57 are prevented from enteringthe inside of the camera body 20. Accordingly, the lens barrel 50 can bemounted to the camera body 20 only from a proper direction (i.e., from adirection substantially parallel to the optical axis).

Consequently, improper mounting, such as connecting the lens barrel 50to the camera body 20 without making the circumferential position of therecessed portion 58 coincident with the protrusion 32 and/or mountingthe lens barrel 50 to the camera body 20 with the lens barrel 50inclined to the camera body 20, can be prevented with reliability.

Upon the lens barrel 50 being mounted to the camera body 20, the contactpins 40, 40 a, 41 and 41 a of the camera body 20 are positioned in therecessed groove 68 of the lens barrel 50, and the rear end of eachcontact 69 of the lens barrel 50 comes in contact with the front end ofthe contact pin 40, 40 a, 41 or 41 a of the camera body 20 whilepressing the corresponding contact pin 40 or 41 from the projectedposition toward the pressed position. Therefore, upon a main switchprovided on the external casing 21 being turned ON, power of the batteryis supplied from the two contact pins 40 and 40 a to the correspondingcontacts 69, and the camera body 20 reads information stored in theaforementioned memory of the lens barrel 50 via the contacts pins 41 and41 a and the contacts 69.

When the lens barrel 50 is detached from the camera body 20, firstly thelock release button 35 in the non-operating position is manually pressedto the operating position to move the lock pin 34 that is in the lockedposition to the unlocked position to move the lock pin 34 out of thelock hole 62. Thereupon, the lens barrel 50 becomes rotatable relativeto the camera body 20, so that the recessed portion 58 is brought to aposition immediately behind the protrusion 32 by rotating the lensbarrel 50 counterclockwise by an angle of approximately 60 degrees asviewed from the front, and the entire lens barrel 50 is moved forwardwith respect to the camera body 20. Thereupon, the lens-side bayonet lug55 moves forward out of the internal space of the external casing 21through the body-side circular-arc opening 28, the lens-side bayonet lug56 moves forward out of the internal space of the external casing 21through the body-side circular-arc opening 29, and the lens-side bayonetlug 57 moves forward out of the internal space of the external casing 21through the body-side circular-arc opening 30, so that the lens barrel50 is disengaged from the camera body 20.

As described above, the present embodiment of the camera body 10, thelens barrel 50 and the camera body 20 can be reliably prevented frombeing improperly mounted to each other.

Moreover, the improper mounting prevention device according to thepresent invention has a simple structure configured of the protrusion 32and the circular arc protrusion 39, which are formed on the camera body20, and the recessed portion 58, which is formed on the lens barrel 50,thus not incurring a significant increase in cost, either.

In addition, since the front ends of the contact pins 40, 40 a, 41 and41 a are positioned behind the body-side mount surface 24 and in frontof the rear surfaces (opposed surfaces) of the body-side bayonet lugs25, 26 and 27, the possibility of the hands, etc., of the user touchingthe contact pins 40, 40 a, 41 and 41 a when the lens barrel 50 isdisengaged from the camera body 20 can be reduced.

Additionally, since the rounded surfaces 55 a, 56 a and 57 a areprovided on the lens-side bayonet lugs 55, 56 and 57, even if therounded surfaces 55 a, 56 a and 57 a are accidentally brought intocontact with the contact pins 40, 40 a, 41 and 41 a when the lens barrel50 is connected to the camera body 20, the contact pins 40, 40 a, 41 and41 a can be prevented from being scratched.

Additionally, since the lens barrel 50 is structured such that thecontacts 69 are positioned inside the recessed groove 68, thepossibility of the hands, etc., of the user touching the contacts 69when the lens barrel 50 is disengaged from the camera body 20 can bereduced.

Additionally, if the hands, etc., of the user touch the contact pins 40,40 a, 41 and 41 a when the lens barrel 50 is disengaged from the camerabody 20, the contact pins 40, 40 a, 41 and 41 a absorb the pressingforce transmitted from the hands, etc., of the user by moving completelyinside the pin support holes against the biasing forces of thecompression coil springs 42, the contact pins 40, 40 a, 41 and 41 a canbe prevented from being damaged. Additionally, the entire contact pins40, 40 a, 41 and 41 a are protected by the circular arc protrusion 39since the contact pins 40, 40 a, 41 and 41 a are positioned completelyinside the pin support holes.

Additionally, although the aforementioned rear space for accommodatingthe battery and controller, etc., is formed in part of the internalspace of the external casing 21 which is located behind the intermediatesupport plate 37, since the front ends of the contact pins 40, 40 a, 41and 41 a are positioned in front of the rear surfaces (opposed surfaces)of the body-side bayonet lugs 25, 26 and 27, the whole camera body 20can be reduced in dimensions in the optical axis direction (slimmeddown) (compared with the case where the front ends of the contact pins40, 40 a, 41 and 41 a are positioned behind the rear surfaces of thebody-side bayonet lugs 25, 26 and 27).

Additionally, since the recessed groove 68, which receives the circulararc protrusion 39 and the contact pins 40, 40 a, 41 and 41 a when thelens barrel 50 is connected to the camera body 20, is formed in the rearof the lens barrel 50, the camera 10 can be reduced in dimension in theoptical axis direction (slimmed down) (compared with the case where therecessed groove 68 that receives the contact pins 40, 40 a, 41 and 41 ais not formed on the lens barrel 50).

Additionally, when the lens barrel 50 is disengaged from the camera body20, a part (upper part) of the image pickup device 44 (the lightreceiving area of the imaging surface thereof) is positioned immediatelybelow the circular arc protrusion 39 (in the vicinity of the innerperipheral side of the circular arc protrusion 39) as viewed from front.Therefore, the circular arc protrusion 39 can prevent fingers of theuser or the like from accidentally touching the image pickup device 44(the light receiving area of the imaging surface thereof) or pressingthe image pickup device 44 (the light receiving area of the imagingsurface thereof).

Additionally, the front of the circular arc protrusion 39 protrudesforward to a position substantially identical to the positions of thebody-side bayonet lugs 25 and 26 in the thickness direction of thecamera body 20 (in a direction parallel to the center axis of theopening hole 22), and the front surfaces of the body-side bayonet lugs25 and 26 and the front surfaces of the circular arc protrusion 39 aresubstantially planar in arrangement (substantially lie in a plane), andaccordingly, even when one accidentally touches the bayonet lugs or theperiphery of the circular arc protrusion 39, the edges of the bayonetlugs can be prevented from hitting finger tips hard or finger tips canbe prevented from being pinched between the edges of bayonet lugs andthe circular arc protrusion 39, which makes it possible to achieve asafer mount structure.

When the lens barrel 50 is mounted to the camera body 20, the circulararc protrusion 39 and the recessed groove 68 have a nested structure inwhich the circular arc protrusion 39 is surrounded by the recessedgroove 68 (the cylindrical portion 54, the inner cylindrical member 66and the bottom of the recessed groove) as shown in FIG. 7. Accordingly,even if light outside the camera 10 enters inside the camera 10 betweenthe body-side mount surface 24 and the lens-side mount surface 53 a, thepossibility of this light reaching the inner peripheral side of thecircular arc protrusion 39 to thereby exert an adverse effect on thelight to be photographed which passes through the aforementioned lensgroups is small.

In addition, as viewed from the front, a portion of the lens-sidebayonet lug 57 lies on the same radial extension line as the contact pin40 a, and the biasing spring S1 biases this portion of the lens-sidebayonet lug 57 rearward. Additionally, as viewed from front, a portionof the lens-side bayonet lug 55 lies on the same radial extension lineas the contact pin 41 a, and the biasing spring S2 biases this portionof the lens-side bayonet lug 55 rearward. Accordingly, it is possible tomake the plurality of contact pins 40, 40 a, 41 and 41 a, which arearranged in a direction parallel to the circumferential direction of thebody-side mount ring 23, come into contact with the correspondingcontacts 69 securely with equal pressure.

Although the present invention has been described using the aboveillustrated embodiment, the present invention can be implemented withvarious modifications made to the above illustrated embodiment.

For instance, a configuration is possible in which theprojection-depression relationship between the protrusion 32 that isprovided on the camera body 20 side and the depression 58 that isprovided on the lens barrel 50 side is reversely applied to the lensbarrel 50 side and the camera body 20 side. In this case, a structure inwhich the above camera-body-side mount structure and lens-barrel-sidemount structure that have been described above are interchanged, namely,a modification is possible in which the lens-side mount ring 52 (thefixed ring portion 53) is provided with the protrusion 32 that isprovided on the body-side mount ring 23, and in which the body-sidemount ring 23 is provided with the recessed portion 58 that is providedon the lens-side mount ring 52.

Additionally, the number of the body-side bayonet lugs formed on thecamera body 20 and the number of the lens-side bayonet lugs formed onthe lens barrel 50 do not have to be three and can be any plural number(however, the number of the body-side bayonet lugs and the number of thelens-side bayonet lugs must be the same). Whatever the number of thebody-side bayonet lugs may be, a biasing spring is installed at the rearof each body-side bayonet lug, while no biasing spring is installed atthe rear of the protrusion 32.

Additionally, it is possible to make only some of the body-side bayonetlugs, only some of the circular-arc openings (which are positionedbetween the body-side bayonet lugs), only some of the lens-side bayonetlugs and only some of the circular-arc openings (which are positionedbetween the lens-side bayonet lugs) different in length from the otherthere of, or to make all the body-side bayonet lugs, all thecircular-arc openings (which are positioned between the body-sidebayonet lugs), all the lens-side bayonet lugs and all the circular-arcopenings (which are positioned between the lens-side bayonet lugs)mutually identical in length, rather than making all the body-sidebayonet lugs, all the circular-arc openings (which are positionedbetween the body-side bayonet lugs), all the lens-side bayonet lugs andall the circular-arc openings (which are positioned between thelens-side bayonet lugs) mutually different in length. However, in eachcase, the distance (circumferential length) between the protrusion 32and the body-side bayonet lug adjacent to the protrusion 32 is set to begreater than the length of the lens-side bayonet lug having the shortestlength.

Additionally, the recessed groove 68 can be made as an annular groovewhich is positioned between the cylindrical portion 54 of the lens-sidebayonet ring 52 and the inner cylindrical portion 66.

Additionally, the protrusion 32 can be provided in one of the circulararc grooves (among the circular arc grooves between the body-sidebayonet lugs) other than the circular arc groove that is the greatest inlength (e.g., can be provided in the circular arc groove which is thesmallest in length).

Additionally, the present embodiment of the camera 10 is a digitalcamera which is provided on the camera body 20 with the image pickupdevice 44; however, the present invention can also be applied to acamera using sliver-salt film.

INDUSTRIAL APPLICABILITY

The present invention has industrial applicability because the lensbarrel can be reliably prevented from being mounted to the camera bodyin an improper manner, in which the lens barrel is inclined, and alsobecause each contact member of the lens barrel and the correspondingcontact member of the camera body can be securely brought into contactwith each other with equal pressure.

REFERENCE SIGNS LIST

-   10 Camera-   20 Camera body-   21 External casing-   22 Opening hole-   23 Body-side mount ring-   24 Body-side mount surface-   25 26 27 Body-side bayonet lug-   28 29 30 Body-side circular-arc opening-   32 Protrusion-   34 Lock pin-   35 Lock release button-   37 Intermediate support plate-   38 Central rectangular aperture-   39 Circular arc protrusion-   40 41 Contact pin (body-side contact portion)-   42 Compression coil spring (contact biaser)-   44 Image pickup device-   50 Lens barrel-   51 Barrel body-   52 Lens-side mount ring-   53 Fixed ring portion-   53 a Lens-side mount surface-   54 Cylindrical portion-   55 56 57 Lens-side bayonet lug-   58 Recessed portion-   59 60 61 Lens-side circular-arc opening-   62 Lock hole-   63 Insulating member-   66 Inner cylindrical member-   67 Circular hole-   68 Recessed groove-   69 Contact (lens-side contact portion)-   S1 S2 S3 Biasing spring (rearward biaser)

1. A camera body having a substantially circular opening formed in afront side thereof, a lens barrel being capable of being attached anddetached to and from said opening and includes a plurality ofcircular-arc-shaped lens-side bayonet lugs which are provided at a rearend of said lens barrel and project toward an outer peripheral side, andwherein said camera body comprises: a plurality of body-side bayonetlugs which project from a peripheral edge of said opening toward aninner peripheral side and are concentric with said lens-side bayonetlugs, wherein said lens-side bayonet lugs are positioned immediatelybehind said body-side bayonet lugs when said lens barrel is mounted tosaid camera body; a plurality of circular-arc openings which are formedbetween said body-side bayonet lugs that are adjacent to one another,wherein said lens-side bayonet lugs pass through said circular-arcopenings when said lens barrel is mounted to said camera body; acircular arc protrusion which is provided inside said camera body andprojects forward, wherein a central portion of said circular arcprotrusion in a lengthwise direction thereof is spaced toward said innerperipheral side from one of said circular arc openings, wherein bothsides of said circular arc protrusion in said lengthwise direction arepositioned at an inner peripheral side of two of said body-side bayonetlugs, respectively, and wherein said circular arc protrusion isconcentric with said body-side bayonet lugs; a plurality of body-sidecontact portions which are provided on a front end surface of saidcircular arc protrusion and are arranged thereon in said lengthwisedirection of said circular arc protrusion, wherein said body-sidecontact portions come into contact with lens-side contact portions whichare provided on said lens barrel when said body-side bayonet lugs arepositioned immediately behind said lens-side bayonet lugs; and tworearward biasers which are provided immediately behind two of saidbody-side bayonet lugs, respectively, to bias and move said lens-sidebayonet lugs rearward, wherein two of said body-side contact portionswhich are located at both ends in said lengthwise direction and said tworearward biasers lie on radial-direction extension lines of saidcircular arc protrusion, respectively, as viewed in an optical axisdirection.
 2. The camera body according to claim 1, wherein saidbody-side contact portions are held in said circular arc protrusion tobe capable of advancing and retracting, and wherein said camera bodycomprises a contact biaser which is provided in said circular arcprotrusion to bias and move said body-side contact portions forward. 3.The camera body according to claim 1, wherein said circular arcprotrusion protrudes to a position substantially identical to a positionof said body-side bayonet lugs in a direction orthogonal to saidbody-side mount surface.
 4. The camera body according to claim 1,wherein a circular arc space is formed between said peripheral edge ofsaid opening of said camera body and said circular arc protrusion, andwherein a circular arc portion of said lens barrel is positioned in saidcircular arc space when said lens barrel is rotated relative to saidcamera body with said body-side bayonet lugs positioned behind saidlens-side bayonet lugs.
 5. The camera body according to claim 2, whereinsaid circular arc protrusion protrudes to a position substantiallyidentical to a position of said body-side bayonet lugs in a directionorthogonal to said body-side mount surface.
 6. The camera body accordingto claim 2, wherein a circular arc space is formed between saidperipheral edge of said opening of said camera body and said circulararc protrusion, and wherein a circular arc portion of said lens barrelis positioned in said circular arc space when said lens barrel isrotated relative to said camera body with said body-side bayonet lugspositioned behind said lens-side bayonet lugs.
 7. The camera bodyaccording to claim 3, wherein a circular arc space is formed betweensaid peripheral edge of said opening of said camera body and saidcircular arc protrusion, and wherein a circular arc portion of said lensbarrel is positioned in said circular arc space when said lens barrel isrotated relative to said camera body with said body-side bayonet lugspositioned behind said lens-side bayonet lugs.
 8. The camera bodyaccording to claim 5, wherein a circular arc space is formed betweensaid peripheral edge of said opening of said camera body and saidcircular arc protrusion, and wherein a circular arc portion of said lensbarrel is positioned in said circular arc space when said lens barrel isrotated relative to said camera body with said body-side bayonet lugspositioned behind said lens-side bayonet lugs.